Threaded-pipe connectors are common in oil, gas, and offshore piping applications. They join pipelines in environments where pipes are frequently coupled and decoupled. The connectors must withstand demanding operating conditions, as they are typically subjected to internal-pressure, axial-pullout, bending, and torsion loads.

It is arduous and time-consuming to begin a threaded-connection simulation with a 3D model even when it is possible. Axisymmetric loadings are significant and can be difficult to solve with contact, and a refined mesh is often necessary for detailed examination of a threaded connection.

Because the first few stages of loading (such as internal pressure and axial pullout) are axisymmetric in nature, and the loads causing nonaxisymmetric deformation (such as bending) occur later, you can use Mechanical APDL's 2D to 3D analysis capability to perform a simpler 2D analysis in the early part of the analysis, followed by a general 3D analysis later.

A 2D to 3D analysis involves extruding a 2D deformed mesh to a new 3D mesh. The program updates the database as necessary, generates contact elements if needed, and transfers boundary conditions, loads, and nodal temperatures from the 2D mesh to the extruded 3D mesh. The program maps all solved variables (node and element solutions) to the new 3D mesh and rebalances solutions for the 3D model automatically. You can then continue the analysis on the 3D model via a multiframe restart, applying nonaxisymmetric loading as desired.